More seriously...
it demonstrates the artficiality of our attempts to separate life into neat little boxes. Everything sort of evolves together. Stuff doesn't have to be physically connected to act like a life "system". The smallest virii and bacteria remain engines of evolution even for the largest animals. The whole ecosphere is constantly morphing and evolving.
I read one time a good way to visualize this by asking what would an alien think if he saw a generational space ship. How would he separate out the life of the system or would he just perceive it has one large entity?